The company hasn't provided details about what went wrong; some features such as search and direct messaging were still presenting problems Tuesday morning.
Jonathan Sun, MIT student: "I thought it would be interesting to look at the world as an outsider." Jonnysun, Twitter celebrity: "*pets a skeleton* u used to b a baby"
Leslie Miley says the company keeps an internal list of colleges and universities it wants to hire from — Stanford, MIT, Carnegie Mellon — and says messaging like that is part of the problem.
Twitter changed its "favorite" icon from a yellow star to a red heart. Twitter users aren't loving it, but NPR's social science correspondent Shankar Vedantam predicts it's just a matter of time.
Pope Francis' social media feeds have blossomed while he's been pontiff, allowing followers to access his messages via Twitter, YouTube and also an app on their smartphones.
Twitter is going after news media that share highlights of U.S. football games without sports organizations' permission. The move shines a spotlight on the notion of fair use of copyrighted content.